tracing: add DEFINE_TRACE_FMT to tracepoint.h

This patch creates a DEFINE_TRACE_FMT to map to DECLARE_TRACE.
This allows for the developers to place format strings and
args in with their tracepoint declaration. A tracer may now
override the DEFINE_TRACE_FMT macro and use it to record
a default format.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>

include/linux/tracepoint.h

@@ -153,4 +153,7 @@ static inline void tracepoint_synchronize_unregister(void)
 	synchronize_sched();
 }
 
+#define DEFINE_TRACE_FMT(name, proto, args, fmt)		\
+	DECLARE_TRACE(name, TPPROTO(proto), TPARGS(args))
+
 #endif